RESUMO
Oligodeoxyribonucleotide probes complementary to hypervariable regions of the 16S ribosomal RNA were designed for specificity toward Streptococcus mutans and Streptococcus sobrinus. The probes were tested for specificity and sensitivity by hybridization with nucleic acid from over 100 mutans and non-mutans oral streptococci and other common oropharyngeal bacteria. Probes designated SM002 and SM010 were 100% sensitive and > 99% specific for S. mutans. Probe SSP001, designed to detect both S. mutans and S. sobrinus, was 88% sensitive and > 99% specific. The probes were able to detect nucleic acid extracted from 3 x 10(4)-1 x 10(5) homologous bacteria. Sensitivity did not vary significantly with the growth state of the cells, except for diminished signals when using nucleic acid extracted from very old cultures. The probes correctly identified 72 S. mutans colonies isolated from 10 volunteer saliva samples, using sugar utilization patterns as a reference standard. Ten isolates resembling S. mutans by colony morphology but not by sugar utilization patterns were correctly distinguished from mutans streptococci by the probes. These results demonstrate that oligonucleotide probes can accurately identify S. mutans in saliva samples.
Assuntos
Sondas de Oligonucleotídeos , Streptococcus mutans/genética , Sequência de Bases , DNA Bacteriano/análise , DNA Bacteriano/genética , Humanos , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , Reação em Cadeia da Polimerase , RNA Ribossômico/genética , Saliva/química , Saliva/microbiologia , Sensibilidade e Especificidade , Streptococcus mutans/isolamento & purificaçãoRESUMO
The relationship between granule density, protein content, and Ca and S contents were studied in two secretory granule fractions, from parotid glands of the rat, previously shown to constitute different stages in granule maturation. The density of the lighter fraction was between 1.133 and 1.142 g/ml, while that of the heavier fraction was greater than 1.142 g/ml. The mean protein content of the denser granules was 12% greater than that of the lighter granules (P less than 0.03), while the dry-mass elemental concentrations in the two granule fractions were unchanged. These results indicate that protein is added to granules during the maturation process (presumably by vesicular traffic), and that the resulting increase in granule density is not driven simply by decrease in water content and/or increased concentrations of inorganic Ca or S in the granules. The elemental concentration values also indicate that the diffusible elements permeate the granule membrane during the fractionation procedures.